User equipment (ue) a apparatus for channel state information feedback in a coordinated multi-point communication system

ABSTRACT

A method of operating a wireless communication system (FIG.  4 ) is disclosed. The method includes receiving a plurality of reference signals from a respective plurality of transceivers ( 402 ). Each of the plurality of reference signals is measured to produce a respective plurality of channel state information (CSI) measurements ( 404 ). An aggregated channel quality indicator (CQI) is calculated from measuring the plurality of reference signals ( 406 ). The aggregated CQI is transmitted to at least one transceiver of the respective plurality of transceivers ( 408 ).

This application is a continuation of prior application Ser. No.13/851,949, filed Mar. 27, 2013, which claims the benefit under 35U.S.C. §119(e) of Provisional Appl. No. 61/615,984, filed Mar. 27, 2012(TI-72062PS2), which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

The present embodiments relate to wireless communication systems and,more particularly, to operation of a Coordinated Multi-Point (CoMP)communication system in which a user equipment (UE) simultaneouslycommunicates with plural base stations (eNB).

With Orthogonal Frequency Division Multiplexing (OFDM), multiple symbolsare transmitted on multiple carriers that are spaced apart to provideorthogonality. An OFDM modulator typically takes data symbols into aserial-to-parallel converter, and the output of the serial-to-parallelconverter is frequency domain data symbols. The frequency domain tonesat either edge of the band may be set to zero and are called guardtones. These guard tones allow the OFDM signal to fit into anappropriate spectral mask. Some of the frequency domain tones are set tovalues which will be known at the receiver. Among these are channelstate information reference signals (CSI-RS). These are referencesignals that are useful for channel measurement at the receiver. In acoordinated multi-point (CoMP) communication system these channel statereference signals are not precoded and are generated by a pseudo-randomsequence generator as a function of the UE cell ID. In the Long TermEvolution (LTE) system of Releases 8, 9, and 10 for conventionalpoint-to-point communication, the cell ID is not explicitly signaled bythe eNB but is implicitly derived by the UE as a function of the primarysynchronization signal (PSS) and secondary synchronization signal (SSS).To connect to a wireless network, the UE performs a downlink cell searchto synchronize to the best cell. A cell search is performed by detectingthe PSS and SSS of each available cell and comparing their respectivesignal quality. After the cell search is performed, the UE establishesconnection with the best cell by deriving relevant system informationfor that cell. Similarly, for LTE Release 11 the UE performs an initialcell search to connect to the best cell. To enable multi-point CoMPoperation, the connected cell then configures the UE by higher-layersignaling with a virtual cell ID for each CSI-RS resource associatedwith each respective base station involved in the multi-point CoMPoperation. The UE generates the pseudo-random sequence for each CSI-RSresource as a function of the virtual cell ID.

Conventional cellular communication systems operate in a point-to-pointsingle-cell transmission fashion where a user terminal or equipment (UE)is uniquely connected to and served by a single cellular base station(eNB or eNodeB) at a given time. An example of such a system is the 3GPPLong-Term Evolution (LTE Release-8). Advanced cellular systems areintended to further improve the data rate and performance by adoptingmulti-point-to-point or coordinated multi-point (CoMP) communicationwhere multiple base stations can cooperatively design the downlinktransmission to serve a UE at the same time. An example of such a systemis the 3GPP LTE-Advanced system. This greatly improves received signalstrength at the UE by transmitting the same signal to each UE fromdifferent base stations. This is particularly beneficial for cell edgeUEs that observe strong interference from neighboring base stations.

FIG. 1 shows an exemplary wireless telecommunications network 100. Theillustrative telecommunications network includes base stations 101, 102,and 103, though in operation, a telecommunications network necessarilyincludes many more base stations. Each of base stations 101, 102, and103 (eNB) is operable over corresponding coverage areas 104, 105, and106. Each base station's coverage area is further divided into cells. Inthe illustrated network, each base station's coverage area is dividedinto three cells. A handset or other user equipment (UE) 109 is shown incell A 108. Cell A 108 is within coverage area 104 of base station 101.Base station 101 transmits to and receives transmissions from UE 109. AsUE 109 moves out of Cell A 108 into Cell B 107, UE 109 may be handedover to base station 102. Because UE 109 is synchronized with basestation 101, UE 109 can employ non-synchronized random access for ahandover to base station 102. UE 109 also employs non-synchronous randomaccess to request allocation of uplink 111 time or frequency or coderesources. If UE 109 has data ready for transmission, which may betraffic data, a measurements report, or a tracking area update, UE 109can transmit a random access signal on uplink 111. The random accesssignal notifies base station 101 that UE 109 requires uplink resourcesto transmit the UE's data. Base station 101 responds by transmitting toUE 109 via downlink 110 a message containing the parameters of theresources allocated for the UE 109 uplink transmission along withpossible timing error correction. After receiving the resourceallocation and a possible timing advance message transmitted on downlink110 by base station 101, UE 109 optionally adjusts its transmit timingand transmits the data on uplink 111 employing the allotted resourcesduring the prescribed time interval. Base station 101 configures UE 109for periodic uplink sounding reference signal (SRS) transmission. Basestation 101 estimates uplink channel quality indicator (CQI) from theSRS transmission.

While the preceding approaches provide steady improvements in wirelesscommunications, the present inventors recognize that still furtherimprovements in transmission of channel state information (CSI) from theUE to the eNB are possible. Accordingly, the preferred embodimentsdescribed below are directed toward this as well as improving upon theprior art.

BRIEF SUMMARY OF THE INVENTION

In a preferred embodiment of the present invention, there is disclosed amethod of operating a wireless communication system. The method includesreceiving a plurality of reference signals (CSI-RS) from a respectiveplurality of transceivers. Each of the respective plurality of referencesignals is measured at the UE to produce a respective plurality ofchannel state information (CSI) estimates. An aggregated channel qualityindicator (CQI) is calculated from the respective plurality of CSIestimates. The aggregated CQI is transmitted to at least one transceiverof the respective plurality of transceivers.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a diagram of a wireless communication system of the prior art;

FIG. 2 is a diagram of a Coordinated Multi-Point communication system ofthe present invention;

FIG. 3 is a diagram showing communication between a user equipment (UE)and a base station (eNB) according to the present invention;

FIG. 4 is a flow chart showing channel state information (CSI) feedbackaccording to a first embodiment of the present invention;

FIG. 5 is a flow chart showing channel state information (CSI) feedbackaccording to a second embodiment of the present invention;

FIG. 6 is a time division multiplex diagram showing CSI feedback on thePhysical Uplink Control Channel (PUCCH) according to the presentinvention;

FIG. 7A is a time division multiplex diagram showing CSI feedback on thePhysical Uplink Control Channel (PUCCH) according to another embodimentof the present invention; and

FIG. 7B is a time division multiplex diagram showing CSI feedback flowon the Physical Uplink Control Channel (PUCCH) according to yet anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Channel state information (CSI) feedback from user equipment (UE) to abase station (eNB) is essential for operating a coordinated multi-point(CoMP) LTE wireless communication system. This CSI feedback facilitatestransmission parameter selection, beamforming, scheduling, interferencealignment, and other factors necessary for an effective communicationsystem. Accordingly, embodiments of the present invention employ channelstate information reference signals (CSI-RS) to derive and feed back anaggregated channel quality indicator (CQI) and/or an aggregatedprecoding matrix indicator (PMI) to improve feedback from the UE to theeNB.

The following abbreviations are used throughout the instantspecification.

-   -   eNB: E-UTRAN Node B or base station    -   UE: User Equipment    -   CSI: Channel State Information    -   CQI: Channel Quality Indicator    -   CSI-RS: Channel State Information Reference Signal    -   E-UTRAN: Evolved Universal Terrestrial Radio Access Network    -   PDCCH: Physical Downlink Control Channel    -   PDSCH: Physical Downlink Shared Channel    -   PUCCH: Physical Uplink Control Channel    -   PUSCH: Physical Uplink Shared Channel    -   CRS: Cell-specific Reference Signal    -   LTE: Long Term Evolution    -   DL DownLink    -   UL UpLink    -   PMI: Precoding Matrix Indicator    -   RI: Rank Indicator    -   RRC: Radio Resource Control    -   PRB: Physical Resource Block    -   QAM: Quadrature Amplitude Modulation    -   IRC: Interference Rejection Combining    -   MRC: Maximum Ratio Combining    -   BIER: Block Error Rate    -   DPS: Dynamic Point Selection    -   JT: Joint Transmission    -   MIMO: Multiple-Input Multiple-Output    -   SNR: Signal to Noise Ratio

Traditional wireless networks operate in a point-to-point transmissionmanner where a UE connects to and receives data from a single basestation. For data transmission, the base station performs downlinkscheduling in order to allocate different frequency resources fordownlink transmission to different UEs, possibly using different coderates, QAM constellation sizes, transmit powers, and MIMO precodingvectors. Downlink scheduling at the eNB is enabled by knowledge ofchannel state information (CSI), which is measured and reported by theUE. In LTE, a CSI report comprises a set of MIMO transmission propertiesrecommended by the UE based on the downlink channel measurement,including rank indicator, precoding matrix indicator, and channelquality indicator. Rank indicator (RI) denotes the number of datastreams (layers) recommended for downlink transmission. The value of RIfeedback can vary from 1 to the minimum of eNB transmit antennas and UEreceive antennas. Precoding matrix Indicator (PMI) indicates the bestprecoding matrix that the UE recommends for downlink transmission.Channel quality indicator (CQI) is an indicator of the quantizedsignal-to-noise ratio which the UE is able to observe when the reportedPMI and RI are used for hypothetical data transmission. In general, oneCSI report comprises RI, PMI, and COI, or a subset thereof. In aconventional wireless network, the reported CSI is per-point CSIcorresponding to a single-cell channel with respect to the connectedbase station. UE selection of the PMI/CQI report is dependent onproprietary UE receiver implementation (e.g. MRC or IRC) and istransparent to the wireless standard. Ideally, the reported PMI/CQIshould optimize a certain performance metric (e.g. maximum sumthroughput) subject to a 10% BLER. This is also used in 3GPP RAN WorkingGroup 4 for setting UE performance requirements for PMI/CQI. The legacyCSI report implicitly reflects both channel and interference components.That is, there is no separate feedback for channel and interference,respectively. Without loss of generality, the reported CQI can bedenoted as a quantization of equation [1],

$\begin{matrix}{{CQI} = \frac{{{u^{\prime}{Hw}}}_{2}^{2}}{I + N}} & \lbrack 1\rbrack\end{matrix}$

where H is the per-point channel, w is the PMI, I is the interferencepower, N is the noise power, a is the receiver equalizer, and ′ is theHermitian operator.

Referring to FIG. 2, there is a diagram of a coordinated multi-point(CoMP) wireless communication system according to the present invention.The communication system includes user equipment (UE) 200 and basestations (eNB) 202, 204, and 206. These base stations may be macro eNB,pico eNB, femto eNB, or other suitable transmission points (TP). For UE200, a plurality of CSI-RS resources is configured based on which the UEcan measure in the downlink channel. Each CSI-RS resource can beassociated by the E-UTRAN with a base station, a remote radio head(RRH), or a distributed antenna. UE 200 is configured by higher-layerRRC signaling with a specific virtual cell identifier (ID) for eachCSI-RS resource. These virtual cell IDs are used by a pseudo-randomsequence generator to generate the channel state reference signals(CSI-RS) corresponding to each CSI-RS resource. UE 200 receives eachvirtual cell ID from higher layer RRC signaling after establishinginitial cell connection with the best cell. The CSI-RS from eNBs 202,204, and 206 are transmitted to UE 200 over wireless channels 208, 212,and 210, respectively.

For CoMP, per-point CSI feedback is a baseline where the UE reports CSIof each base station separately. Since each base station is associatedwith a CSI-RS resource, this is equivalent to per-CSI-RS-resourcefeedback. Several different implementations of per-CSI-RS-resourcefeedback are possible. In one embodiment, per-point COI and per-pointPMI are reported for each configured CSI-RS resource. Alternatively,per-point CSI information is explicitly reported for a subset of basestations. For other base stations without explicit per-point CSIfeedback, per-point CSI information can be inferred or estimated fromother CSI reports (e.g. aggregated CQI) when available. It is possiblethat per-CSI-RS-resource CSI feedback comprises a subset of RI, PMI, andCQI information. In one embodiment, at least per-point PMI pertaining tolegacy LTE definition is reported for each configured CSI-RS resource.Such PMI is an indication of the spatial characteristics for each CoMPmeasurement point and important for all CoMP transmission schemes. Itcould be used for single-point beamforming in dynamic point selection,for interference alignment in coordinated beamforming and scheduling,and for coherent and non-coherent beam combining in joint processing. Inaddition, per-point COI is needed for all CoMP schemes to enable pointselection, perform interference alignment in coordinatedbeamforming/scheduling and joint transmission. In one embodiment,per-point CQI is reported for each configured CSI-RS resource. Thisprovides the maximum scheduling flexibility. With per-point CQI of allCSI-RS resources, the eNB scheduler is able to dynamically switchbetween different CoMP transmission schemes and/or dynamically fall backto single-point transmission, based on quickly changing systemconditions such as cell loading, traffic type, or UE mobility. Inanother embodiment, per-point CQI is reported for one or a subset ofCSI-RS resources. For instance, a UE-centric feedback for DPS may reportCQI for the selected point plus a point selection indicator, while CQIfor other points is not reported. For points without CQI feedback, CQIis either unavailable or has to be predicted by the base station fromother feedback information (e.g. aggregated CQI) which reduces theaccuracy of per-point CQI.

Since per-point CQI is derived under single-point transmissionhypothesis, it is likely to be less accurate for CoMP link adaptationsuch as JT, where signals from multiple transmission points are combinedeither coherently or non-coherently at the UE receiver. In contrast,aggregated CQI aims to improve the link adaptation accuracy of CoMPjoint transmission. With this scheme, an aggregated COI is calculated bythe UE to reflect the downlink SNR when all base stations jointlytransmit data to the UE. Assume a CoMP measurement set comprising Kpoints, where per-point PMI is reported for each point UE 200 receivesthe composite signal y in equation [2] from K transmission points. HereH is the channel state and v_(l) is the precoding hypothesis for each ofK eNBs. In the example of FIG. 2 K=3, but in a practical CoMP network Kmay be greater or less than 3. In one embodiment, aggregated COI isderived assuming precoding with vs on the k-th measurement point (e.g.k-th CSI-RS resource), where vi is the PMI feedback corresponding to thek-th measurement point. Essentially, such an aggregated COI correspondsto incoherent CoMP-JT beamforming with the following received signal y.

$\begin{matrix}{y = {{HV} = {\left\lbrack {H_{1},H_{2},{\ldots \mspace{14mu} H_{k}}} \right\rbrack \begin{bmatrix}v_{1} \\v_{2} \\\; \\v_{K}\end{bmatrix}}}} & \lbrack 2\rbrack\end{matrix}$

In another embodiment, aggregate CQI is derived assuming precoding withe^(j0) ^(k) v_(k) on the k-th measurement point (e.g. k-th CSI-RSresource), where v_(k) is the PMI feedback, and e, is the inter-pointco-phasing feedback corresponding to the k-th point. Essentially, suchan aggregated CQI corresponds to coherent CoMP-JT beamforming with thefollowing received signal y in equation [3].

$\begin{matrix}{y = {{HV} = {\left\lbrack {H_{1},H_{2},{\ldots \mspace{14mu} H_{K}}} \right\rbrack \begin{bmatrix}{^{{j\theta}_{1}}v_{1}} \\{^{{j\theta}_{2}}v_{2}} \\\; \\{^{{j\theta}_{K}}v_{K}}\end{bmatrix}}}} & \lbrack 3\rbrack\end{matrix}$

The aggregated CQI reflects a boosted SNR value when all transmissionpoints jointly transmit data to the UE. It is possible that theaggregated CQI may be larger than the summation of per-point CQIs. It isalso possible to report multiple aggregated CQIs, each of which isderived under different CoMP transmission set hypotheses. For instance,assume the CoMP measurement set has three transmission points (TP1, TP2,and TP3). The UE may report an aggregated CQI corresponding to eachcombination of two points in the measurement set and/or report anaggregated CQI corresponding to the entire CoMP measurement set Multipleaggregated CQIs, if reported on the PUCCH channel, can be time-divisionmultiplexed on different PUCCH transmissions at different timeinstances. Otherwise, if multiple aggregated CQIs are to be reported onthe PUSCH channels, they can be transmitted in the same PUSCHtransmission, or transmitted in different PUSCH transmissions.

UE 200 transmits the aggregated COI to primary eNB 202 over channel 214.UE 200 may optionally transmit the aggregated CQI over channels 216 and218 to eNBs 206 and 204 of the CoMP network.

The aggregated CQI is computed by the UE based on the downlink qualityassociated with the aggregated channel over M transmission points alongwith their respective precoding hypotheses. The M transmission pointsare a subset within set size K. When M=K, only one aggregated CQI isreported corresponding to all transmission points of the set K.Alternatively, when M<K, there are

$\quad\begin{pmatrix}M \\K\end{pmatrix}$

possibilities. In this case, it is possible to report either a few orall of the respective CQIs.

There are multiple ways to configure the aggregated CQI information bythe eNB. The aggregated COI mainly targets link adaptation forcoherent/non-coherent joint transmission but is not required forcoordinated beamforming/scheduling and dynamic point selection. Fromthis perspective, aggregated CQI can be configured UE-specifically byhigher layer signaling. On the other hand, whether aggregated COI shouldbe explicitly reported also depends on the decision of per-pointfeedback. As one possibility, the UE may report per-point CQI for allpoints plus aggregated CQI. As another possibility, the UE may reportper-point CQI for one or a subset of points plus aggregated COL.

Turning now to FIG. 3, there is a diagram showing communication betweenuser equipment (UE) 300 and a base station (eNB) 320 according to thepresent invention. UE 300 may be a cell phone, computer, or otherwireless network device. UE 300 includes a processor 306 coupled to amemory 304 and a transceiver 310. Processor 306 may include severalprocessors adapted to various operational tasks of the UE includingsignal processing and channel measurement and computation. The memorystores application software that the processor may execute as directedby the user as well as operating instructions for the UE. Processor 306is also coupled to input/output (I/O) circuitry 308, which may include amicrophone, speaker, display, and related software. Transceiver 310includes receiver 312 and transmitter 314, suitable for wirelesscommunication with eNB 320. Transceiver 310 typically communicates witheNB 320 over various communication channels. For example, transceiver310 sends uplink information to eNB 320 over physical uplink controlchannel PUCCH and physical uplink shared channel PUSCH.

Correspondingly, transceiver 310 receives downlink information from eNB320 over physical downlink control channel PDCCH and physical downlinkshared channel PDSCH.

Base station 320 includes a processor 326 coupled to a memory 324, asymbol processing circuit 328, and a transceiver 330 via bus 336.Processor 326 and symbol processing circuit 328 may include severalprocessors adapted to various operational tasks including signalprocessing and channel measurement and computation. The memory storesapplication software that the processor may execute for specific usersas well as operating instructions for eNB 320. Transceiver 330 includesreceiver 332 and transmitter 334, suitable for wireless communicationwith UE 300. Transceiver 330 typically communicates with UE 300 overvarious communication channels. For example, transceiver 330 sendsdownlink information to UE 300 over physical downlink control channelPDCCH and physical downlink shared channel PDSCH. Correspondingly,transceiver 330 receives uplink information from UE 300 over physicaluplink control channel PUCCH and physical uplink shared channel PUSCH.

FIG. 4 is a flow chart showing channel quality indicator (CQI) feedbackaccording to a first embodiment of the present invention. Operationbegins with UE initialization 400 when the UE enters the CoMPconfiguration. The UE determines a primary eNB and synchronizes withother suitable eNBs as indicated by the CoMP configuration. The UEdetermines the virtual cell ID for each CSI-RS resource. At block 402,the UE determines CSI-RS sequence for plural CSI-RS resources. The UEmeasures 404 per-point CSI from each of the CSI-RS resources. The UEcalculates 406 an aggregated CQI from the plural CSI-RS resources. TheUE subsequently transmits 408 the per-point CSI and aggregated COI tothe primary eNB. Responsively, the primary eNB selects and transmits 410appropriate communication parameters to the UE. At block 412, the UEcommunicates with the plurality of eNBs subject to the receivedcommunication parameters.

FIG. 5 is a flow chart showing precoding matrix indicator (PMI) feedbackaccording to a second embodiment of the present invention. Operationproceeds as previously described with respect to FIG. 4. At block 500,however, the UE transmits per-point PMI hypotheses and an aggregated CQIreport to the primary eNB. Responsively, the primary eNB selects andtransmits 410 appropriate communication parameters to the UE. At block412, the UE communicates with the plurality of eNBs subject to thereceived communication parameters.

Referring to FIG. 6, there is a time division multiplex diagram showingper-point CSI and aggregated CQI feedback on the Physical Uplink ControlChannel (PUCCH) according to one embodiment of the present invention. Afirst per-point CSI₁ measurement is transmitted at 600 followed by asecond per-point CSI₂ at 602. Here, the subscript indicates a particularper-point CSI-RS source in the CoMP configuration. Other per-point CSImeasurements (not shown) are subsequently transmitted followed by anaggregated CQI report at 604. At blocks 606 and 608, a second set ofper-point measurements of CSI and CSI₂ are respectively transmittedfollowed by a second aggregated COI report 610.

FIG. 7A is a time division multiplex diagram showing CSI feedback on thePhysical Uplink Control Channel (PUCCH) according to another embodimentof the present invention. Here, a first per-point CSI₁ measurement istransmitted at 700. A second per-point CSI₂ is transmitted at 702together with an aggregated CQI report. Other per-point CSI measurements(not shown) may also be transmitted. A second set of per-pointmeasurements is then transmitted beginning with CSI₁ at block 704. Nextper-point measurement CSI₂ is transmitted at 706 together with a secondaggregated CQI report.

Turning now to FIG. 7B, there is a time division multiplex diagramshowing PMI feedback flow on the Physical Uplink Control Channel (PUCCH)according to yet another embodiment of the present invention. Here, afirst per-point PMI₁ hypothesis and CQI₁ measurement are transmitted at710. A second per-point PMI₂ hypothesis is transmitted at 712 togetherwith an aggregated COI report. Other per-point PMI hypotheses (notshown) may also be transmitted. A second set of per-point hypotheses isthen transmitted beginning with PMI₁ and per-point CQI₁ report at block714. Next, per-point hypothesis PMI₂ is transmitted at 716 together witha second aggregated CQI report.

Still further, while numerous examples have thus been provided, oneskilled in the art should recognize that various modifications,substitutions, or alterations may be made to the described embodimentswhile still falling with the inventive scope as defined by the followingclaims. Other combinations will be readily apparent to one of ordinaryskill in the art having access to the instant specification.

1-27. (canceled)
 28. A user equipment (UE) comprising: circuitry forreceiving a plurality of reference signals from a respective pluralityof base stations; circuitry for measuring the plurality of referencesignals to generate an aggregated channel quality indicator (CQI) for asubset of the plurality of reference signals, wherein the aggregated CQIreflects a link quality associated with an effective aggregated channelof a subset of the respective plurality of base stations; circuitry formeasuring each of the plurality of reference signals to generate arespective plurality of per-point channel state information (CSI);circuitry for transmitting the aggregated CQI and at least one of theper-point CSI to at least one of the respective plurality of basestations.
 29. A user equipment (UE) as in claim 28, wherein theper-point CSI comprises a per-point precoding matrix indicator (PMI).30. A user equipment (UE) as in claim 29, wherein the per-point CSIcomprises a per-point channel quality indicator (CQI), and wherein theper-point CQI is derived under a hypothesis of single-pointmultiple-input multiple-output (MIMO) beamforming on a base station ofthe respective plurality of base stations using a precoding matrixindicted by the respective per-point PMI.
 31. A user equipment (UE) asin claim 29, wherein the aggregated CQI is derived under a hypothesis ofjoint transmission from the respective plurality of base stations,wherein each of the plurality of base stations uses a respectiveprecoding matrix indicated by the respective per-point PMI.
 32. A userequipment (UE) as in claim 28, wherein the per-point CSI comprises aper-point co-phasing factor.
 33. A user equipment (UE), comprising thesteps of: circuitry for receiving a plurality of reference signals froma respective plurality of transceivers; circuitry for measuring theplurality of reference signals to generate an aggregated channel qualityindicator (CQI), wherein the aggregated COI reflects a link qualityassociated with an effective aggregated channel of the respectiveplurality of transceivers, wherein the aggregated COI is derived under ahypothesis of joint transmission from the respective plurality oftransceivers, wherein precoding by each of the plurality of transceiversuses a respective precoding matrix indicated by the respective per-pointPMI, which is phase rotated by a respective per-point co-phasing factor;circuitry for measuring each of the plurality of reference signals togenerate a respective plurality of per-point channel state information(CSI) wherein the per-point CSI comprises a per-point co-phasing factor,circuitry for transmitting at least one of the per-point CSI to the atleast one transceiver, and circuitry for transmitting the aggregated CQIand at least one of the per-point CSI to at least one transceiver of therespective plurality of transceivers
 34. A user equipment (UE) as inclaim 29, wherein the aggregated CQI and the at least one per-point CSIare transmitted on Physical Uplink Control Channel (PUCCH) in differentuplink subframes.
 35. A user equipment (UE) as in claim 30, wherein theaggregated COI and the at least one per-point PMI are transmitted on aPhysical Uplink Control Channel (PUCCH) in a same uplink subframe.
 36. Auser equipment (UE), comprising: circuitry for receiving a plurality ofreference signals from a respective plurality of base stations;circuitry for measuring each of the plurality of reference signals toproduce a respective plurality of channel state information (CSI)signals for a subset of the plurality of reference signals; circuitryfor calculating an aggregated channel quality indicator (CQI) from thesubset of the respective plurality of CSI signals; and circuitry fortransmitting the aggregated CQI and at least one of the CSI signals toat least one base station of the respective plurality of base stationswherein the aggregated CI and the at least one of the CSI signals aretransmitted on a Physical Uplink Control Channel (PUCCH) in differentuplink subframes.
 37. A user equipment (UE), comprising: circuitry forreceiving a plurality of reference signals from a respective pluralityof base stations; circuitry for measuring each of the plurality ofreference signals to produce a respective plurality of channel stateinformation (CSI) signals for a subset of the plurality of referencesignals; circuitry for calculating an aggregated channel qualityindicator (CQI) from the subset of the respective plurality of CSIsignals; and circuitry for transmitting the aggregated CQI and at leastone of the CSI signals to at least one base station of the respectiveplurality of base stations, wherein the aggregated COI and the at leastone of the CSI signals are transmitted on a Physical Uplink ControlChannel (PUCCH) in a same uplink subframe.
 38. A user equipment (UE),comprising: circuitry for receiving a plurality of reference signalsfrom a respective plurality of base stations; circuitry for measuringeach of the plurality of reference signals to produce a respectiveplurality of channel state information (CSI) signals for a subset of theplurality of reference signals; circuitry for calculating an aggregatedchannel quality indicator (CQI) from the subset of the respectiveplurality of CSI signals, wherein each of the respective plurality ofCSI signals comprises a per-point CSI; and circuitry for transmittingthe aggregated COI to at least one base station of the respectiveplurality of base stations.
 39. A user equipment (UE), comprising:circuitry for receiving a plurality of reference signals from arespective plurality of base stations; circuitry for measuring each ofthe plurality of reference signals to produce a respective plurality ofchannel state information (CSI) signals for a subset of the plurality ofreference signals; circuitry for calculating an aggregated channelquality indicator (CQI) from the subset of the respective plurality ofCSI signals, wherein each of the respective plurality CSI signalscomprises a per-point precoding matrix indicator (PMI); and circuitryfor transmitting the aggregated CQI to at least one base station of therespective plurality of base stations.
 40. A user equipment (UE),comprising: circuitry for transmitting a first reference signal to auser equipment (UE); circuitry for receiving a precoded matrix indicator(PMI) from the UE in response to the first reference signal; circuitryfor receiving an aggregated information signal from the UE in responseto a subset of the first reference signal, a second reference signalfrom a second base station, and a third reference signal from a thirdbase station, wherein the aggregated information signal and the PMI arereceived on a Physical Uplink Control Channel (PUCCH) in differentuplink subframes; and circuitry for transmitting communicationparameters to the UE in response to the aggregated information signal.41. A user equipment (UE), comprising: circuitry for transmitting afirst reference signal to a user equipment (UE); circuitry for receivinga precoded matrix indicator (PMI) from the UE in response to the firstreference signal; circuitry for receiving an aggregated informationsignal from the UE in response to a subset of the first referencesignal, a second reference signal from a second base station, and athird reference signal from a third base station, wherein the aggregatedinformation signal and the PMI are received on a Physical Uplink ControlChannel (PUCCH) in a same uplink subframe; and circuitry fortransmitting communication parameters to the UE in response to theaggregated information signal.
 42. A user equipment (UE), comprising:circuitry for transmitting a first reference signal to a user equipment(UE); circuitry for receiving a per-point channel state information(CSI) signal from the UE in response to the first reference signal;circuitry for receiving an aggregated information signal from the UE inresponse to a subset of the first reference signal, a second referencesignal from a second base station, and a third reference signal from athird base station; and circuitry for transmitting communicationparameters to the UE in response to the aggregated information signal.43. A user equipment (UE) as in claim 22, wherein the aggregatedinformation signal and the per-point CSI signal are transmitted on aPhysical Uplink Control Channel (PUCCH) in different uplink subframes.44. A user equipment (UE), comprising: circuitry for receiving aplurality of reference signals from a respective plurality of basestations; circuitry for measuring each of the plurality of referencesignals to generate a respective plurality of per-point channel stateinformation (CSI); circuitry for measuring the plurality of referencesignals to generate an aggregated channel quality indicator (CQI),wherein the aggregated CQI reflects a link quality associated with aneffective aggregated channel of the respective plurality of basestations; circuitry for transmitting at least one of the per-point CSIto at least one of the plurality of base stations; and circuitry fortransmitting the aggregated CQI to at least one of the plurality of basestations.
 45. A user equipment (UE), comprising: circuitry for receivinga plurality of reference signals from a respective plurality of basestations; circuitry for measuring the plurality of reference signals togenerate at least two aggregated channel quality indicators (CQIs), eachof which is derived under different Coordinated Multi-Point (CoMP)transmission set hypotheses, wherein the aggregated CQIs reflect a linkquality associated with an effective aggregated channel of subsets ofthe respective plurality of base stations; and circuitry fortransmitting the aggregated CQIs to at least two of the respectiveplurality of base stations.
 46. A user equipment (UE), comprising:circuitry for determining channel state information (CSI)-RS sequencesfor plural channel state information (CSI)-RS resources; circuitry formeasuring channel state information (CSI) from the plural CSI-RSresources; circuitry for calculating an aggregated channel qualityindicator (CQI) from the measured plural CSI-RS resources; and circuitryfor transmitting per-point-CSI and the aggregated CQI.
 47. A userequipment (UE) of operating a user equipment (UE), the UE performingeach of the following, comprising: circuitry for determining channelstate information (CSI)-RS sequences for plural channel stateinformation (CSI)-RS resources; circuitry for measuring channel stateinformation (CSI) from the plural CSI-RS resources; circuitry forcalculating an aggregated channel quality indicator (CQI) from themeasured plural CSI-RS resources; and circuitry for transmittingper-point precoding matrix indicator (PMI) and the aggregated CQI.